Although polycystic ovarian syndrome (PCOS) is associated with risk factors for cerebrovascular disease, the available evidence does not demonstrate increased stroke mortality, and it has been suggested that some protective mechanisms must be operating in these women. Haemodynamic changes have been demonstrated in the pelvic vessels and aorta in this syndrome, but there have been no studies of the cerebral circulation. Since insulin resistance is a central feature of PCOS, it is of interest that cerebral blood flow may be altered in diabetic subjects. The present study was designed to assess internal carotid artery haemodynamics in women with PCOS, asymptomatic women with polycystic ovaries (PCO women) and healthy controls. Mean internal carotid pulsatility index, measured using pulsed Doppler ultrasound under standardized conditions, was significantly lower in 35 PCOS and 15 PCO women than in the 18 controls. This was also shown on multiple regression analyses. Peak systolic velocity did not differ between groups. In view of the difficulty of interpreting pulsatility index in low-impedance vascular beds, the ‘back’ pressure was calculated and found to be lower in women with polycystic ovaries. This is the first demonstration of lower pulsatility index and back pressure (suggestive of reduced vascular tone) in the cerebral circulation of these women, independent of blood pressure, insulin resistance and other endocrine or metabolic factors. Changes in internal carotid haemodynamics may offset the risk of cerebrovascular disease commonly associated with polycystic ovaries.

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